Only Chinese, digital, and English can be entered in the JavaScript control input box

1. Background of the problem

Encounter a problem: there is an input box that requires only Chinese, numeric, and English (that is, filter special strings)

2. JS Code

function Checkusername ()

{

Regular expressions

var reg = new RegExp ("^[a-za-z\d\u4e00-\u9fa5]+$");

Get the value in the input box

var username = document.getElementById ("username"). Value.trim ();

Determine what is in the input box

if (Username.length >0)

{

Alert ("Please input Chinese, digital and English!) ");

Enter illegal characters, empty the input box

$ ("#username"). Val ("");

}

}

3. Page code

<input type= "text" id= "username" onkeyup= "Checkusername()"/>

Only Chinese, digital, and English can be entered in the JavaScript control input box